Lubricating oils



Patented Feb. 18, 1936 UNITED STATES PATENT OFFlCE LUBRICATING OILS tionof Delaware No Drawing. Application August 21, 1934, Serial No. 740,786

17 Claims.

This invention relates to the manufacture of lubricating oilcharacterized by a low pour test and/or an increased viscosity index.

The invention contemplates the preparation of mineral lubricating oilhaving a reduced pour test and other desirable qualities fromlubricating oil stock, such as those derived from mixed base andparafiin base crudes and the like, by the addition to the lubricatingoilof a pour point depressant material.

contemplates the addition to a lubricating oil of a small proportion ofan esterified hydroxy stearic acid.

The invention also contemplates the preparation of mineral lubricatingoil having an increased viscosity index from naphthene base crudes aswell as mixed base and paraflin base crudes, by the addition to thelubricating oil of a minor proportion of an esterified hydroxy stearicacid.

Lubricating oil stocks derived fromparaflin and mixed base crudescontain appreciable amounts of wax and, therefore, have arelatively highpour test unless a substantial amount of this wax is is, there is arelatively smallchange inthe viscosremoved. The removal of this wax isusually ac-- .complished by cold settling, filtration or centrifuging.However, lubricating oil stocks, after dewaxing by these processes, maystill retain some wax, and may have a pour test abov'e 15 F. and up toabout F. The removal of further quantities of wax from these stocks inorder to further reduce the pour test necessitates expensive further'processing.

On the other hand, the presence of a certain amount of wax in alubricating oil may be paratively fiat temperature-viscosity curve. Thatity of the oil between temperatures of say 100 V F. and 210 F.Consequently, it is of advantage employed.

to add to the oil a material which will have the effect of reducing thepour test or cold test to the desired extent without the necessity ofentirely removing the remaining wax.

We have discovered that the esterification product of a hydroxy stearicacid with a fatty acid constitutes an effective material for additon toa partially dewaxed mineral lubricating oil of this character to lowerthe pour point thereof. The hydroxy stearic acid may be esterified witha higher fatty acid, such as stearic, palmitic and the like. Verysatisfactory results have been secured by esterifying dihydroxy stearicacid with stearic acid. However, similar esterification products ofmono-hydroxy stearic acid can be The invention particularly the freefatty acid content had dropped to 3%.

As a specific example of the present invention, the product obtained byesterifying dihydroxy stearic acid with stearic acid is described. Thedihydroxy stearic acid may be conveniently obtained by oxidation ofoleic acid. For example, a water solution of 84 g. of oleic acid in 1500cc. of water, to which was added 33 g. of potassium hydroxide, wascooled to around 0 C.; and then a previously prepared solutioncontaining 84 g. of potassium permanganate dissolved in 1500 cc. 1 ofwater was added slowly with agitation, such that the temperature did notrise above 10 C. The mixture was stirred for an hour after the solutionhad been added, and then was allowed to stand for a period of time. Theprecipitate 1 of manganese dioxide was filtered off and the solutionacidified with dilute sulphuric acid, which caused the precipitation ofthe dihydroxy stearic acid. This was filtered, dried, extracted withether and again dried.

20 g. of the dihydroxy stearic acid was then heated with 16.8 g. ofcommercial stearic acid to a temperature of around 240 C. while underhigh vacuum equivalent to about 20 mm. Hg. The temperature wasmaintained at 240 C. for 2 hours. The product was then found to containabout 5% free fatty acid (figured as stearic acid). It was again heatedto 240 C. and maintained at this temperature for an hour, at which timeAfter cooling, the reaction product was dissolved in about 300 cc. ofdiethyl ether, filtered, and the filtered ethereal solution washed firstwith sodium carbonate solution and then with distilled water. The etherwas then evaporated and the product heated at 110 C. for 1 day, and thencooled over calcium chloride.

The substance so obtained is a light amber colored elastic jelly; andapparently is a complex portions of about 0.25-l.5 by weight. Thereaction product is preferably added to the -oil by heating therewith ata temperature of around 100 C., and then filtering to remove theinsoluble portion. The following results were obtained when thisreaction product was added to a partially dewaxed paraflin baselubricating oil having a pour point of +20 F.

Pour, F. 100 cc. oil-Hess than 0.25 g. esterification product 0, -5 100cc. oil+less than 0.5 g. esterification product -15, --10 100 cc.oil+less than 1.0 g. esterification product -30,

In the production of high grade lubricating oils, it is well known thata relatively small change in the viscosity of the oil betweentemperatures of say 100 F. and 210 F., is desirable. In other words, itis advantageous for the oil to have a relatively flatviscosity-temperature curve, which means that the oil has a highviscosity index as defined by Dean and Davis in their article inChemical and Metallurgical Engineering, Vol. 36, page 618. Improvementin lubricating oils has heretofore been accomplished by refining, as bythe use of selective solvents which are efiective in extracting orseparating naphthenic constituents from paraflinic constituents, therebyproducing a resulting raflinate of increased viscosity index. Thisprocedure involves expensive processing, and results in a reduced yieldof finished oil.

The addition of an esterified hydroxy 'stearic acid of the characterdescribed above-in controlled proportions to a naphthene base orparaflin base lubricating oil is also found to materially increase theviscosity index thereof. When the esterification product is added toimprove the viscosity index of a lubricating oil, a proportion of about545% by weight is generally employed.

The following results were obtained by the addition of the mentionedamounts of the esterification product of dihydroxy stearic acid withstearic acid to naphthene base lubricating oils:

Weight in grams of Saybolt Saybolt Vol. ol oil inc.e. eotcriflcationvllcosit viscosit Viscosity product atiqf at 210 index added In theabove examples, a substantial proportion of the esteriflcation productadded to the.

mineral oil was not dissolved, and was filtered out before testing.Consequently, the actual proportion of viscosity index improverdissolved is substantially-less than the amount indicated in the abovetable.

Where the expression paraflin base lubricating oil" is used in theaccompanying description and claims, it is to be understood that thisrefers to an oil of the mixed base or mid-continent type as well as anoil of the paraflin base or Pennsylzeantia type, unless the contraryappears from the We are aware that it has heretofore been proposed toadd hydroxy stearic acid, or the zinc or magnesium salts thereof, to amineral lubrieating oil as a pour point depressant. The presentinvention is distinguished by the use of a substantially neutralesterification product of the hydroxy stearic acid, thereby avoidingobjections inherent in the use of free acids or metal salts in an oil,particularly when adapted for use as 2 motor oil, while at the same timesecuring increased efiectiveness and other advantages.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

We claim:

1. A lubricating oil of improved character comprising a mixture of apetroleum lubricating oil with a minor proportion of an esterifiedhydroxy stearic acid.

2. A lubricating oil of improved character comprising a mixture of apetroleum lubricating oil with a minor proportion of an esterifieddihydroxy stearic acid.

3. A lubricating oil of improved character comprising a mixture of apetroleum lubricating oil with a minor proportion of the esteriflcationproduct of a hydroxy stearic acid with a fatty acid.

4. A lubricating oil of improved character comprising a mixture of apetroleum lubricating oil with a minor proportion of the esterificationproduct of a hydroxy stearic acid with a higher fatty acid.

5. A lubricating oil of improved character comprising a mixture of apetroleum lubricating oil with a minor proportion of the esterificationproduct of a hydroxy stearic acid with stearic acid.

6. A lubricating oil of improved character comprising a mixture of apetroleum lubricating oil with a minor proportion of the esterificationproduct of a dihydroxy stearic acid with stearic acid.

'7. A lubricating oil having a pour point of about 0 F. or below,comprising a partially dewaxed paraffin base petroleum lubricating oilmixed with about 0.25-1.5% by weight of an esterified hydroxy stearicacid.

8. A lubricating oil having a pour point of about 0 F. or below,comprising a partially dewaxed base petroleum lubricating oil mixed withabout 025-1.5% by weight of the esterification product of dihydroxystearic acid with stearl'c acid.

9. A lubricating oil of improved viscosity index, comprising a petroleumlubricating oil admixed with about 515% by weight of an esterifiedhydroxy stearic acid.

10. A lubricating oil of improved viscosity index, comprising apetroleum lubricating oil admixed with about 515% by weight of theesteriflcation product of dihydroxy stearic acid with stearic acid.

11. A pour point depressant material and viscosity index improver for amineral lubricating 011 comprising an esterified hydroxy stearic acid.

12. A pour point depressant material and viscosity index improver for amineral lubricating oil comprising the esteriflcation product of ahydroxy stearic acid with a higher fatty acid.

13. A pour point depressant material andviscosity index improver for amineral lubricatin oil comprising the esteriflcation product ofdihydroxy stearic acid with stearic acid.

14. The method of improving a mineral lubricating oil, which comprisesesterifying a hydroxy stearic acid, and dissolving the esterifiedproduct 11111 a minor proportion in a mineral lubricating o 15. Themethod of improving a mineral lubrieating oil. which comprises reactinga hydroxy stearic acid with a higher fatty acid to produce an esterifiedhydroxy stearic acid and dissolving the esterified product in a minorproportion in a mineral lubricating oil.

16. The method of improving a mineral lubrieating oil, which comprisesreacting hydroxy stearic acid with stearic acid to esterify the former,and dissolving the esterified product in a minor proportion in a minerallubricating oil.

17. The method of improving a mineral lubricating oil, which comprisesoxidizing oleic acid to dihydroxy stearic acid, esterifying thedihydroxy stearic acid with stearic acid, heating the esterifled productwith a. mineral lubricating oil, and filtering the resultant oil toremove undissolved residue.

ERNEST F. PEVERE. CLIFFORD G. LUDEMAN.

